Affects on visual search performance of individual differences in fixation time and number of fixations

Abstract

The purpose of this study was to provide a basis for improving individual visual performance of inspectors. The relationship between the correct count rate and eye movements of subjects when they counted dots arranged on samples presented for different lengths of time were analysed mainly to determine individual differences. Subjects' eye movements were measured with a corneal reflectance eye camera and analysed frame by frame with a video motion analyser. It was found that accuracy of visual inspection does not depend on length of search time and that a fast search time is not incompatible with a slow search speed. Furthermore, fixation time and number of fixations were considered the main factors governing accuracy of visual inspection. When limited time is allowed for search, a search strategy of prolonging the fixation time leads to high performance and consequently shorter inspection time. Several other findings were obtained which appear important in obtaining accurate information rapidly.